Battery life

That is NOT the battery voltage.
It IS the charging voltage and it can vary from 14.5 or so down to maybe 13.6 and be just fine.
To measure the battery, the car must be OFF.

The 12 V battery will last longer if:
You drive it every day for 30 minutes or more.
OR
You get a smart tender type battery maintainer to connect when the car will not be used for more than a few days.
If you drive it regularly, you should not worry (too much) about the 12 V battery unless you know that it is over 5 years old.

 

are you thinking that is the hybrid battery voltage?

 

thr charging voltage of the 12 volt battery isn't really helpful unless there is a charging problem.

the best test for the 12 volt is done with a load tester. you can put a volt meter on it and turn the headlights on, or take it to an auto parts store for a free test. or buy a load tester.

the battery icon on the dash shows you a representation of the hybrid battery state of charge, but no actual numbers.
for hybrid battery health, you can get some info from an app like dr. prius.